Question

C++

In this recitation assignment, you are given the definition of a Class, called Value, which represents values of operands in the language to implement its interpreter in Programming Assignment 3. These include values for the three defined types in the language: INT, FLOAT, and BOOL, as well as the string literal. The objective of defining the Value class is to facilitate constructing an interpreter for the language which evaluates expressions and executes statements using C++. In RA 8, you are required to implement some of the overloaded operators of the Value class in order to enable testing this class separately as a unit before using it in the construction of the interpreter in PA3. You are required to implement the overloaded operators for Subtraction, Multiplication, Less-Than, and AND operations. The semantic rules governing the evaluation of expressions in the language are summarized below: The binary operations for addition, subtraction, multiplication, and division are performed upon two numeric operands (i.e., INT, FLOAT) of the same or different types. If the operands are of the same type, the type of the result is the same type as the operator’s operands. Otherwise, the type of the result is FLOAT. The binary logic operations for the AND and OR operators are applied on two Boolean operands only. The LTHAN and GTHAN relational operators and the EQUAL operator operate upon two operands of compatible types. The evaluation of a relational expression, based on LTHAN or GTHAN operators, or an Equality expression, based on the Equal operator, produce either a true or false value. The unary sign operators (+ or -) are applied upon one numeric operand (i.e., INT, FLOAT). While the unary NOT operator is applied upon a one Boolean operand (i.e., BOOL).

Answer 1

The question pertains to implementing overloaded operators (-, *, <, &&) in a Value class for an interpreter in C++. Operators should handle types according to provided semantic rules, promoting to FLOAT where necessary for numeric operations and returning BOOL for logical and relational operations.

Step-by-step explanation:

In the context of implementing an interpreter for a programming language in C++, a Value class is used to represent the different types of values operands can take, such as INT, FLOAT, BOOL, and string literals. This question focuses on the implementation of overloaded operators within the Value class to facilitate expression evaluation and statement execution in an interpreter. The operators to be implemented include Subtraction (-), Multiplication (*), Less-Than (<), and AND (&&), following the specified semantic rules.

Implementing Overloaded Operators in the Value Class

• The Subtraction and Multiplication operators should handle both INT and FLOAT types, promoting the result to FLOAT if necessary.
• The Less-Than operator should compare numeric values or compatible types, resulting in a BOOL.
• The AND operation is a Boolean logic operation, applying exclusively to BOOL operands and yielding a BOOL result.

Examples

For subtraction, if both operands are of type INT, the result should also be INT. If one operand is FLOAT, the result should be FLOAT. Similarly, for multiplication, the result's type is determined by the rule of type promotion to FLOAT if operands are of different numeric types. The Less-Than operator should evaluate operands and return a BOOL that indicates whether the first operand is less than the second. Lastly, the AND operator should perform logical conjunction on two BOOL values.

Answer 2

An example of the usage of the Value class in C++ with the specified overloaded operators for Subtraction, Multiplication, Less-Than, and AND operations is shown Below

#include <iostream>

#include <string>

enum Type {

INT,

FLOAT,

BOOL,

STRING

};

class Value {

public:

Type type;

union {

int intValue;

float floatValue;

bool boolValue;

std::string stringValue;

};

// Constructors

Value(int value) : type(INT), intValue(value) {}

Value(float value) : type(FLOAT), floatValue(value) {}

Value(bool value) : type(BOOL), boolValue(value) {}

Value(const std::string& value) : type(STRING), stringValue(value) {}

// Overloaded operators

Value operator-(const Value& rhs) const {

// Subtraction operation

if (type == FLOAT || rhs.type == FLOAT) {

return Value(floatValue - rhs.toFloat());

} else {

return Value(intValue - rhs.toInt());

}

}

Value operator*(const Value& rhs) const {

// Multiplication operation

if (type == FLOAT || rhs.type == FLOAT) {

return Value(floatValue * rhs.toFloat());

} else {

return Value(intValue * rhs.toInt());

}

}

Value operator<(const Value& rhs) const {

// Less-Than operation

if (type == FLOAT || rhs.type == FLOAT) {

return Value(floatValue < rhs.toFloat());

} else {

return Value(intValue < rhs.toInt());

}

}

Value operator&&(const Value& rhs) const {

// AND operation

if (type == BOOL && rhs.type == BOOL) {

return Value(boolValue && rhs.toBool());

} else {

// Handle error or return a default value

return Value(false);

}

}

// Helper functions to convert between types

float toFloat() const {

return (type == FLOAT) ? floatValue : static_cast<float>(intValue);

}

int toInt() const {

return (type == INT) ? intValue : static_cast<int>(floatValue);

}

bool toBool() const {

return boolValue;

}

};

int main() {

// Example usage

Value a = 5;

Value b = 3.5;

Value result1 = a - b;

std::cout << "Subtraction Result: " << result1.toFloat() << std::endl;

Value result2 = a * b;

std::cout << "Multiplication Result: " << result2.toFloat() << std::endl;

Value result3 = a < b;

std::cout << "Less-Than Result: " << (result3.toBool() ? "true" : "false") << std::endl;

Value bool1 = true;

Value bool2 = false;

Value result4 = bool1 && bool2;

std::cout << "AND Result: " << (result4.toBool() ? "true" : "false") << std::endl;

return 0;

}

So the above code is one that helps defines the Value class with its member variables and constructor.

Therefore, It also provides the implementations for the overloaded operators for Subtraction, Multiplication, Less-Than, and AND operations.